Car trouble · Heat & A/C

My vents smell musty

A damp, moldy or dirty-sock smell comes out of the vents, usually when you first turn on the fan or A/C.

Not urgent

A starting point, not a diagnosis. Most parts stores read check-engine codes and test batteries for free.

Likely causes — tick the parts you want

  1. A dirty cabin air filter

    most likely · Most people can do this

    How to check: Pull the cabin air filter, usually behind the glovebox. A dark, damp or leaf-packed filter is a common source of the smell.

  2. Mold growing on the A/C evaporator

    possible · Most people can do this

    How to check: If the smell is strongest the first minute the A/C runs and a new filter did not fix it, moisture on the evaporator is growing mold.

  3. A clogged A/C drain tube

    less likely · A mechanic’s job

    How to check: On a hot day with the A/C running, look under the passenger side for a steady drip of water. No drip and a damp passenger floor suggest a blocked drain.

Your car — the counter needs this

If the counter doesn’t have a part, your shopper asks them to order it under your name and messages you the order number. When it comes in, send someone to collect it.

Not quite it?

My A/C blows warm airMy heater blows cold air
My vents smell musty — likely causes and the parts · DriverRuns